Re: Any saa711x users out there?

[Franklin Meng <fmeng2002@yahoo.com>]

I also have a device that has the SAA7113 chip in it.  Kworld 315U.  

I suggested a patch to add a an s_power function to the code but it looks like the patch didn't work.  I have to do some cleanup to it and resubmit it.  

Franklin Meng

--- On Thu, 2/4/10, Devin Heitmueller <dheitmueller@kernellabs.com> wrote:

> From: Devin Heitmueller <dheitmueller@kernellabs.com>
> Subject: Re: Any saa711x users out there?
> To: "Andy Walls" <awalls@radix.net>
> Cc: "Linux Media Mailing List" <linux-media@vger.kernel.org>
> Date: Thursday, February 4, 2010, 8:34 PM
> Hey Andy,
> 
> On Thu, Feb 4, 2010 at 11:15 PM, Andy Walls <awalls@radix.net>
> wrote:
> > Hmmm.  The AGC (or static gain level?) of the
> amplifier in the SAA7113
> > before the anti-alias filter may be set too high
> causing the clipping
> > (intermods) there.  It may be worth looking at the
> gain setting for that
> > amp.
> 
> It's possible.  One thing I did as a test though was I
> did a capture
> of the i2c traffic under Windows (using the same reference
> video
> source), and then compared the register programming (via
> some scripts
> I whipped up).  There were some other registers that
> were different,
> but the only one that made *any* visible difference in the
> output was
> the AA flag.
> 
> > The visible effects of the anti-alais filter could
> possibly be:
> >
> > 1. Less range of color, if high freqs of the color get
> attenuated.
> > (Most people likely will not perceive this as most
> people are not that
> > sensitive to small color variations.)
> >
> > 2. Loss of rapid variations in Luma - softer edges
> between light and
> > dark areas on a scan line - if higher freqs of the
> Luma get attenuated.
> >
> > but given that the anti-alais filter is essentially
> flat out to about
> > 5.6 MHz and has a slow rolloff (only 3 dB down at
> about 6.9 MHz), I
> > doubt anyone would ever notice it is on with NTSC.
> 
> To give you a better idea of what I'm talking about, look
> at this image:
> 
> http://imagebin.org/83458
> 
> The above image was taken with the generator via the
> s-video input
> (ruling out the possibility that it's any sort of product
> of
> intermodulation).
> 
> For the sake of comparison, here's the exact same signal
> source
> against an a similar em28xx design but with the tvp5150.
> 
> http://imagebin.org/83459
> 
> > Since you have a signal generator, you should run
> experiments with PAL-D
> > and SECAM-D with a grid containing vertical lines
> since those both have
> > a 6.0 MHz video bandwidth.  SECAM also has FM color,
> so you might see
> > the greatest affect of an antialias filter on color on
> the Cyan color
> > bar in SECAM-D.
> 
> Believe it or not, I'm actually having trouble with the
> generator
> right now with anything but NTSC.  I'm going back and
> forth with
> Promax on repair options.  So I cannot do any PAL or
> SECAM testing
> right now.
> 
> On a separate note, I really should look at extending the
> v4l2
> capture-example to a version that let's me do a direct
> capture of the
> YUYV frame and convert the output into a zero-loss RGB
> format.  It's
> too easy to be mislead by things the applications are doing
> like
> deinterlacing, rescaling, blending, and compression of the
> screenshot
> when saving to a file.
> 
> Devin
> 
> -- 
> Devin J. Heitmueller - Kernel Labs
> http://www.kernellabs.com
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>